Debt Payoff Calculator
Adjust the inputs below. Results update as you type.
How it works
Debt payoff planning is about sequencing: which balance you attack first, how much extra you can pay each month, and how interest accrues while you work the plan. Snowball (smallest balance first) optimizes for early wins; avalanche (highest APR first) usually minimizes interest. This calculator lets you compare timelines and interest under a fixed monthly budget across multiple debts.
Enter each balance, APR, and minimum payment, then set an extra amount you can commit above the sum of minimums. The model applies minimums across all debts and routes the extra to the active target until it clears, then rolls that payment capacity to the next target. Watch total interest and debt-free date—not only the first victory date.
Consolidation or balance transfers can help when the new rate and fees truly lower total cost and you avoid reloading revolving debt. If motivation is the bottleneck, snowball may beat a theoretically optimal avalanche you abandon. Re-run the plan whenever a rate changes or you can raise the monthly budget.
Input guidance
- List every revolving or installment balance you will include in the plan.
- Use current APRs and true minimums from statements.
- Commit an extra monthly amount you can sustain after essentials.
The formula
Payoff time solves the amortization formula for n given the balance, rate, and payment: n = −ln(1 − balance·r/payment) / ln(1+r). Extra payments lower the effective balance faster.
Worked example
A $10,000 debt at 18% with $300/month takes about 41 months and $2,200 in interest. Raising it to $450/month cuts it to about 25 months and roughly $1,250 in interest.
More examples to test
- $18,000 across 3 debts with $450 monthly + $1,200 annual lump sum: compare avalanche vs snowball timeline.
- Increase monthly extra payment by $100 and measure interest saved and debt-free date change.
How to interpret results
Optimize for the plan you will finish. Avalanche usually minimizes interest; snowball can improve adherence through faster clears.
When this can be inaccurate
Variable APRs, fees, hardship programs, and new charges after the plan starts will change outcomes.
Change history
- July 2026: Documented snowball vs avalanche routing and consolidation caveats.
- June 2026: Multi-debt timeline engine reviewed.
Site-wide corrections also appear on the corrections log.
Consolidate debt at a lower rate
May reduce your monthly payments.
Frequently asked questions
How much faster does extra payment help?+
Disproportionately. Because interest is charged on the balance, every extra dollar removes future interest, compounding your progress.
What if I have several debts?+
List them all, pay every minimum, then attack one at a time — highest rate (avalanche) or smallest balance (snowball).
Should I save or pay debt first?+
Keep a small emergency buffer, then prioritize high-interest debt, since paying off 18% debt is a guaranteed 18% return.
How should I use this result?+
Treat it as a planning estimate. Compare at least two realistic scenarios, then confirm with statements, quotes, or a qualified professional before acting.
How often should I refresh assumptions?+
Refresh whenever rates, income, costs, or policy limits change materially, and before making irreversible commitments.
Guided next steps
Want the full workflow? Use this calculator inside a step-by-step guide.
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